Hitherto, a method of crushing natural stone in adequate size, mixing this with a resin, etc., casting this into a mold frame and hardening, and grinding and fabricating, according to need, into artificial stone has been known. And, regarding such artificial stone, various approaches have been taken with respect to the formulating ratio of components of resin, etc., and natural stone, the nature these components, and the conditions for production such as depressuring and pressuring or temperature control.
For example, regarding resin to be mixed with crushed product of natural stone, using unsaturated polyester and methyl methacrylate (MMA) resin has been proposed, and regarding the entire composition, artificial stone composed of an inorganic particle component of large particle diameter and an inorganic fine particle component of small particle diameter, and a resin component of a small ratio lower than 15 wt % of the total amount, has also been developed by the inventor of this application.
In the case of this newly developed artificial stone, making the best used of the feature that the amount of the resin component used as the binder is small and using a fine particle body of natural stone, etc., a product having a dense structure, a color tone with a transparent feel and a color tone with a deep feel, and yet being superior in moldability despite the small amount of the resin component, capable of being molded into arbitrary shapes, has been obtained.
However, despite such conventional approaches, regarding the molding of artificial stone to curved surfaces and the molding to more complex deformed shapes, areas to be improved remain.
The reason for this is that regarding the curved surface molding (R-type molding), for example, the method of casting into a curved-surface-like mold and hardening, and polish-fabricating afterward, and the method of polish fabricating after the cutting out by R-shaped slice fabrication are known, but the polish fabrication of the curved surface state is very expensive, raising the product price, and preventing widespread practical use.
As an improved method, a method of heat-softening and bend fabricating after polish fabricating the plate-like forming body has been proposed, but in the conventional methods, a serious defect has occurred that air bubbles remaining inside the forming body and residual monomer of the resin component expand by heating, locally deforms the softened part, and whitens the product.
Similarly, in the conventional technology, there is a problem in that it is impossible to produce artificial stone product formed to curved surfaces and deformed shapes simply at a low cost, without causing deformation and whitening, and there was a need for immediate improvement in this regard.